Converting petroleum oils



June 20, 41933. D.R. STEVENS Er AL 1,915,206

CONVERTING PETROLEUM oILs l Filed July 24, 1931 SMN/nto 7 llRJS-efvenLIR.HdanQ/s,

Patented .Pune 20, 1933 UNITED STATES PATENT OFFICE.y

DONALD R. STEVENS, 0F PITTSBURGH, PENNSYLVANIA, AND JULIUS R. ADAMS, Oli

WESTFIELD,'MASSACHUSETTS, ASSIGNORS TO GULF REFINING COMPANY, 0F PITTS-BURGH, PENNSYLVANIA, A CORPORATIO N 0F TEXAS CONVERTING PETROLEUM OILSApplication led July 24,

This invention relates to converting petroleum oils; and it comprises amethod of utilizing aluminum chlorid in the conversion of high boilingoils into lower boiling oils with a minimizaton of loss as gas and cokeand high utilization of the aluminum chlorid,

wherein a mixture of liquid high boiling oil and aluminum chlorid 1sheated to a temperature of aboutv 380 to 420 C. and is maintained l atthat temperature to allow equilibrium to become established to asubstantial degree, vaporization being minimized as far as possible,usually by employing a pump pressure of the order of 2500 pounds duringthe equilibration; the equilibrized mixture-being afterwards distilledto recover the low 4boiling oils formed; all as more fully hereinafterset forth and as claimed.

In the usual method of making gasoline and kerosene from gas oil andother relatively heavy oils by'distilling with aluminum chlorid, theoperation is often described as depending on a disturbed equilibrium.rIhe term is in a sense misleading since no equilibrium is everinstituted in the whole body of original oil. In hot gas oil, aluminumchlorid produces`rearrangement of the hydrocarbon groups resulting inthe formation of new'lighter oils and heavier coils and this tendency ifuninterrupted comes to some sort of equilibrium or balance between thetwo. l By removing the light oils as fast as they are formed, while. atendency to equilibration remains and is utilized, there is at no timeanyl realiequilibrium. At any instant, the aluminum chlorid can beregarded as beginning equilibration of a new body of oil, the heavierresidue left in the still. In the usual operation, a charge of oil inthe still is mixedwith aluminum chlorid and progressively distilled. Thecharge thickens and changes and finally becomes pitch or coke holdingthe aluminum chlorid. The

r distillate carries with it some gas, often 1931. Serial N0. 552,974.1.

largely butane and usually contains a very large proportion of verylight constituents. The residue in the still is of no value and isdiscarded. In this operation insofar as gas and coke are formed there isa waste. So to speak, the division of the original oil into light andheavy products has gone too far each way. The yield of low boiling oilsof medium volatility is not as satisfactory as could be desired. Nor isthe converting power of the aluminum chlorid utilized to a maximum.

In the stated operation there is no opportunity for any equilibrium tobe produced; the whole charge is not maintalned in contact with thealuminum chlorid for a sufHcient time to accomplish this. What is trueof this batch operation is also true of certain proposed continuousmethods wherein aluminum chlorid and oil are sent through hot tubes as aflowing current. Vapor forms as before and once formed it has littlechance for reaction with the aluminum chlorid, this remaining mainly inthe liquid phase.- Asl before, the net result is an overhead distillateof low boiling oil and a residue of pitch or coke. Insofar as this pitchor coke is formed, it represents a loss of material; a loss of oil whichhas not been transformed into gasoline and kerosene.

In ideal operation, the whole body of oil,

without subtraction of any reaction product, would be maintained incontact with the aluminum chlorid at a high temperature untilequilibrium is obtained until the converting action of the aluminumchlorid is utilized to a maximum. The new oil produced would have Widelydifferent distilling characteris-- yas vention. Vive have found thatbetter results as regards utilization of aluminum chlorid, conversion ofoil and minimization of the wasteful formation of gas and coke result bymaintaining, as far as is practical, the whole body of oil in liquidform in contact with the aluminum chlorid for a reasonable time; a timewhich is of the order of 6 to 15 minutes. The temperature ofequilibration is advantageously around 380o to 420o C. In order tomaintain the oil, as far as possible, in the liquid form at thistemperature we use a pressure of the order of 2500 pounds. The pressuremay drop to 1000 pounds or go to 3000, but on the whole around 2500pounds represents the best economic balance. Pressure by gases from anoutside source or autogenously produced pressure from the system itselfmay be used, but it is better for the present purposes to rely on pumppressure and arrange heating conditions so as to minimize production ofvapor as far as possible. The reaction mixture may, for example, becontained in an autoclave without much vapor space or it may fiowthrough a system of hot tubing at such a rate and for such a period offlow as will enable heating the oil in the system at the describedtemperature for at least 6 minutes; that is so that every portion of themixture will have at least 6 minutes heating. A heating time of 15minutes is better. `With a tubular heating system, a flooding fe-edshould be used; i. e. the tube should bc kept as full'of liquid aspossible.

Under the conditions stated, there is but little formation of coke. Themagma of oi and aluminum chlorid introduced into the tubes Hows throughwithout forfeiting its liquidity until the pressure is released beyondthe tubes and distillation takes place. This retention of liquiditydepends on allowing no substantial formation of vapor and gas. If muchvapor formation be permitted, coke will form and will tend to plug thetubes.

In the foregoing description we have had in mind more particularly hightemperatures of the order of 400 C. with correspondingly quick action.At these high temperatures high pressure is necessary to restrainproduction of vapor. y The heating time at these temperatures is. asstated. about 6 to 15 minutes. By slower operation, affording more timefor reaction. much lower temperatures may be employed.

As illust-rating the results obtained under different conditions, a 36B. solar oil from a mid continent crude with an admixture of 3 per centanhydrous aluminum chlorid gave a yield of about 37.5 per cent ofmarketable gasoline on heating for 15 minutes at 2500 pounds pumppressure and at 400o C., under conditions permitting little formation ofvapor. Under the same conditions with the 1 housing 8 past relief valve9 to same amount of aluminum chlorid, the same solar oil heated forv 15minutes at 380 C. gave 36 per cent gasoline. The pressure used wassomewhat higher, being ,about 3000 pounds. On the other hand, with lessaluminum chlorid and less time at a somewhat higher temperature, asomewhat greater yield of gasoline was obtained. The time was 10minutes, the temperature 410 C. and the pressure 2400 pounds, with ayield of 42 per cent gasoline.

In the accompanying illustration we have shown, more or lessdiagrammatically, certain apparatus within the purview of our inventionand susceptible of use in performing the described process.

lin this showing the drawing is a view in vertical section.

Describing the elements in the order of their use, element 1 is a pumpof any suitable type taking oil from inlet 2 and delivering it throughcoil 3 within a heating housing 4. The pump is of such a type as isadapted to deliver oil at the outlet of the apparatus at a pressure ofbetween 1000 and 3000 pounds. Passing upward through the heating coilhot oil passes through conduit 5 whereit is joined by aluminum chloridintroduced through inlet 6. It is convenient to introduce the aluminumchlorid as a pumpable magma of heavy oil and aluminum chlorid. Pumpingmeans, not shown, are used in this event. The hot mixture of oil andaluminum chlorid which may contain aluminum chlorid in about theproportion of 2 to 3 per cent passes through heating coil 7 in furnaceber 10. This may be of any suitable type for promoting disengagement ofvapors.

Advantageously, the top portion 11 is arranged with shelves or packingdevices. As shown, the lower portion of the tower 12 is unobstructed andis provided with drainage means 13 valved at 14. Vapors formed in thetower pass through conduit 15 to condenser 16. The liquid withdrawn at14 is a fairly fluid mixture of aluminum chlorid and oil. But littlecoke is formed in the present operation. This mixture may be submittedto distillation to obtain a further proportion of gasoline and keroseneor it may be otherwise utilized.

What we claim is:

1. In the conversion of high boiling oils to low boiling oils with theaid of aluminum chlorid the process which comprises making a mixture ofaluminum chlorid and oil, the amount of aluminum chlorid being of theorder of 2 to 3 per cent and heating such mixture in liquid phase to atemperature aroun 400o C. in the absence of added hydrogen, heatingbeing for a period ranging from 6 to 15 minutes and under a pressureadapted to restrain to a minimum the formation of vapor, this pressurebeing generally between a flash chaml amount of aluminum chlorid 1000and 3000 pounds; and thereafter distillin the treated mixture.

2. n the conversion of high boiling oils to low boiling oils the processwhich comprises heating a mixture of heavy oil in liquid phase with 2 to3 per cent aluminum chlorid in the absence of added hydrogen to atemperature of about 400 C. under a pressure of about 2500 pounds,heating being for a period of at least 6 minutes.

3. 1n the conversion of high boiling oils to low boiling oils theprocess Which comprises heating a mixture of heavy oil in liquid phaseWlth 2 to 3 per cent aluminum chlorid in the absence of added hydrogento a temperature ranging from about 380 to 420 C. until equilibrium issubstantially attained, products of reaction being kept in the oil bodyas nearly as possible and the Whole operation being conducted undersufiicient pressure and with conditions restraining substantialformation of vapor; and thereafter distilling the reacting mixture toobtain low boiling oils.

4. In the conversion of high boiling oils to low boiling oils with theaid of aluminum chlorid, the process which comprises makingl a mixtureof aluminum chlorid and oil, the being of the order of 2 to 3 per centand heating such mixture in liquid phase to a temperature around 400oC., in the absence of added hydrogen, heating being for a period rangingfrom 6 to minutes and under a pressure adapted to restrain to a minimumthe formation of vapor, this pressure being generally between 1000 and3000 pounds; and thereafter distilling the treated mixture Without atany time during the process subjecting the material treated totemperatures substantially above 420 C.

5. In the conversion of high boiling oils to low boiling oils theprocess which comprises heating a mixture of heavy oil in liquid phasewith 2 to 3 per cent aluminum chlorid in the absence of added hydrogentoa temperature of about 400 C. under a pressure of about 2500 pounds,heating being for a period of at least 6 minutes; the said process beingconducted without at any time during the process subjecting the materialtreated to temperatures substantially above 420 C.

6. In the conversion of high boiling oils to low boiling oils theprocess which com- DONALD a; STEVENS. JULiUs a. Ans.

prises heating a mixture of heavy o`il in liquid phase with 2 to 3 percent aluminum chlorid in the absence of added hydrogen to a temperatureranging from about 380 to 420 C. until equilibrium is substantiallyattained, products of reaction being kept in the oil body as nearly aspossible and the whole operation being conducted under suilicientpressure and with conditions restraining substantial formation of vapor;and thereafter

